1. The BGA Rework Process
Due to the solder joints of a BGA type device being inaccessable, BGA rework stations are required to remove such devices when they fail.
During the rework process the device is locally heated to a temperature at which the solder joints under the component melt. When this happens the BGA is removed from the PCB by means of a vacuum pickup.
A replacement component is then processed by applying solder paste typically via a small stencil to the PCB pads, and then using the rework station the new component is aligned and placed in position. The area is again heated to enable solder reflow and securing the component.
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2. BGA Rework Applications
The primary application for BGA rework stations or SMD rework stations in general is for replacement and rework of BGA type device, however the rework station can be used for removal of other advanced packages and QFP's.
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3. BGA Rework Station Types
BGA rework stations offer various levels of complexity and automation.
The primary concern is the method of heating. IR is used in a great number of systems to perform the reflow of the components, however whilst this is OK for many plastic BGA packages, ceramic and other high density devices require alternative heating such as forced convection.
Split vision systems involving the use of prisms allow the underside of the component to be overlayed onto the PCB pads to help with alignment. There is a variety of these systems available.
Some rework stations also have options for reballing BGA's and for paste printing using quick connect modules.
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4. Troubleshooting BGA Rework Problems
Proper control over the various reflow profiles when reworking BGA's will ensure good results. However it is easy to overheat the PCB and cause warpage or secondary reflow to adjacent components if the profiling is not accurate. Another important factor is accurate and complete solder paste deposition, as the small stencils when used are prone to aperture blockage and understencil smear resulting in test failures.
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5. Expert Advice..
Please visit individual supplier websites for further detailed information. Browse manufacturers BGA rework stations here
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